Hmmm Bryan Singer hasn't announced another actor joining the cast of DOFP since his casting announcement of Lady Gaga.

If this is the final cast (excluding minor roles and the actor that will portray President Nixon), the cast isn't too big. 16 actors and 14 characters aren't a lot especially this is already the 7th movie in the series and they are mixing the original cast and the cast of FC. X3 still takes the cake for having the most amount of characters.